I have boxes of 240gr boattail jacketed HP bullets in 30 cal. Are there safe loads with Unique powder to get near sub-sonic velocities? If so, is a filler required to keep the powder contained?
I shoot these bullets in a .300 Whisper (now called Blackout) at sub-sonic and would like to try them in the '06. Thanks in advance.
Ray

I shoot the Lyman 311284 which weigh 210gr in alloy I use . I'm pushing it 1700 - 1800 as at that speed it still groups well @ 200yds . 1903 Springfield 1 in 10 twist 4 groove Rem '41 barrel . At lesser ranges same bullet will shoot well @ 1500 with SR 4759 , Unique , 4227 , 4198 or 2400 . I use H4895 in my load of 26.0grs with a Rem 9 1/2 primer . I do use a small tuft of dacron to keep powder near primer as it seems to reduce spreads . Another good 200yd load with same bullet is 32.0grs IMR 4064 . I've had very good luck with H4895 cast loads in the old milsurp rifles .

Most of your loading data manuals will not do a sub-sonic load with a copper jacket bullet in fear of having a "Squib" !!

A LARGE 220gr copper coated bullet has a LOT of surface area to cause friction
in weapons with different chamber and barrel spec's and that is just asking for trouble with a load going too slow for safety.

The SLOWEST load that I have ever seen for a 220 JSP bullet was from Speer and it was...............
at 1721 fps.

That 240gr is for a 300 BO with a 7-16" barrel.......
a 30-06 has a standard 22-24" barrel. Quite a different animal.

You need to try some lead bullets for SS loads, for your safety
in that large powder holding 30-06 case.

I would not even try that idea of yours, with a vise and a long string !!

While on the PD many years ago, I developed a subsonic load for a suppressed Model 700 Remington in 30/06. The 1 in 10" twist rate limited the maximum weight bullet choice to a 190 grain spitzer boat tail at 1,100 fps.

The above load was very accurate out to 200 yards, but that was it. After 200 yards it went wherever it wanted. Of course 200 yards is plenty of range for a subsonic load.

Another note is that from full power loads to the subsonic load, you added 12 MOA to the scope for a zero at 100 yards. With suppressor screwed on, you had to add another 12 MOA for a total of 24 MOA elevation from the standard configuration to the suppressed and subsonic configuration. This was with a hunting weight barrel.

I will also note that if you plan to reuse your cases over any length of time, the headspace length of the cases will shrink. This is not due to the firing pin strike as many shooters believe, but due to the pressure in the primer pocket being higher than the pressure in the case. This is what forces the case forward to shrink it. The solution is to enlarge your flash hole by at least 25 percent. Cases so modified will only need to be neck sized for much of their life as the HS will remain constant. Segregate these case for only low pressure loads. I have been doing this for over 40 years with perfect results.

Back when I developed the 190 grain MK load, there was no option of the 300 Blackout. To be honest, I wouldn't pursue the Ought-Six option as you already have a Blackout and its small case capacity and rapid rifling twist is ideal for your need of a subsonic load.